Inhibitors of IAP

ABSTRACT

Novel inhibitors of IAP that are useful as therapeutic agents for treating malignancies and have the general formula I: 
                         
wherein R 1 , R 2 , R 3 , R 4 , R 5  and R 6  are as described herein.

SEQUENCE LISTING

The instant application contains a Sequence Listing which has beensubmitted electronically in ASCII format and is hereby incorporated byreference in its entirety. Said ASCII copy, created on Apr. 1, 2014, isnamed CURGEN-0223_SL.txt and is 1,613 bytes in size.

The present invention relates to organic compounds useful for therapyand/or prophylaxis in a mammal, and in particular to inhibitors of IAPproteins useful for treating cancers.

Apoptosis or programmed cell death is a genetically and biochemicallyregulated mechanism that plays an important role in development andhomeostasis in invertebrates as well as vertebrates. Aberrancies inapoptosis that lead to premature cell death have been linked to avariety of developmental disorders. Deficiencies in apoptosis thatresult in the lack of cell death have been linked to cancer and chronicviral infections (Thompson et al., (1995) Science 267, 1456-1462).

One of the key effector molecules in apoptosis are the caspases(cysteine containing aspartate specific proteases). Caspases are strongproteases, cleaving after aspartic acid residues and once activated,digest vital cell proteins from within the cell. Since caspases are suchstrong proteases, tight control of this family of proteins is necessaryto prevent premature cell death. In general, caspases are synthesized aslargely inactive zymogens that require proteolytic processing in orderto be active. This proteolytic processing is only one of the ways inwhich caspases are regulated. The second mechanism is through a familyof proteins that bind and inhibit caspases.

A family of molecules that inhibit caspases are the Inhibitors ofApoptosis (IAP) (Deveraux et al., J Clin Immunol (1999), 19:388-398).IAPB were originally discovered in baculovirus by their functionalability to substitute for P35 protein, an anti-apoptotic gene (Crook etal. (1993) J Virology 67, 2168-2174). IAPs have been described inorganisms ranging from Drosophila to human. Regardless of their origin,structurally, IAPs comprise one to three Baculovirus IAP repeat (BIR)domains, and most of them also possess a carboxyl-terminal RING fingermotif. The BIR domain itself is a zinc binding domain of about 70residues comprising 4 alpha-helices and 3 beta strands, with cysteineand histidine residues that coordinate the zinc ion (Hinds et al.,(1999) Nat. Struct. Biol. 6, 648-651). It is the BIR domain that isbelieved to cause the anti-apoptotic effect by inhibiting the caspasesand thus inhibiting apoptosis. As an example, human X-chromosome linkedIAP (XIAP) inhibits caspase 3, caspase 7 and the Apaf-1-cytochrome Cmediated activation of caspase 9 (Deveraux et al., (1998) EMBO J. 17,2215-2223). Caspases 3 and 7 are inhibited by the BIR2 domain of XIAP,while the BIR3 domain of XIAP is responsible for the inhibition ofcaspase 9 activity. XIAP is expressed ubiquitously in most adult andfetal tissues (Liston et al, Nature, 1996, 379(6563):349), and isoverexpressed in a number of tumor cell lines of the NCI 60 cell linepanel (Fong et al, Genomics, 2000, 70:113; Tamm et al, Clin. Cancer Res.2000, 6(5):1796). Overexpression of XIAP in tumor cells has beendemonstrated to confer protection against a variety of pro-apoptoticstimuli and promotes resistance to chemotherapy (LaCasse et al,Oncogene, 1998, 17(25):3247). Consistent with this, a strong correlationbetween XIAP protein levels and survival has been demonstrated forpatients with acute myelogenous leukemia (Tamm et al, supra).Down-regulation of XIAP expression by antisense oligonucleotides hasbeen shown to sensitize tumor cells to death induced by a wide range ofpro-apoptotic agents, both in vitro and in vivo (Sasaki et al, CancerRes., 2000, 60(20):5659; Lin et al, Biochem J., 2001, 353:299; Hu et al,Clin. Cancer Res., 2003, 9(7):2826). Smac/DIABLO-derived peptides havealso been demonstrated to sensitize a number of different tumor celllines to apoptosis induced by a variety of pro-apoptotic drugs (Arnt etal, J. Biol. Chem., 2002, 277(46):44236; Fulda et al, Nature Med., 2002,8(8):808; Guo et al, Blood, 2002, 99(9):3419; Vucic et al, J. Biol.Chem., 2002, 277(14):12275; Yang et al, Cancer Res., 2003, 63(4):831).

Melanoma IAP (ML-IAP) is an IAP not detectable in most normal adulttissues but is strongly upregulated in melanoma (Vucic et al., (2000)Current Bio 10:1359-1366). Determination of protein structuredemonstrated significant homology of the ML-IAP BIR and RING fingerdomains to corresponding domains present in human XIAP, C-IAP1 andC-IAP2. The BIR domain of ML-IAP appears to have the most similaritiesto the BIR2 and BIR3 of XIAP, C-IAP1 and C-IAP2, and appears to beresponsible for the inhibition of apoptosis, as determined by deletionalanalysis. Furthermore, Vucic et al., demonstrated that ML-IAP couldinhibit chemotherapeutic agent induced apoptosis. Agents such asadriamycin and 4-tertiary butylphenol (4-TBP) were tested in a cellculture system of melanomas overexpressing ML-IAP and thechemotherapeutic agents were significantly less effective in killing thecells when compared to a normal melanocyte control. The mechanism bywhich ML-IAP produces an anti-apoptotic activity is in part throughinhibition of caspase 3 and 9. ML-IAP did not effectively inhibitcaspases 1, 2, 6, or 8.

Since apoptosis is a strictly controlled pathway with multipleinteracting factors, the discovery that IAPs themselves are regulatedwas not unusual. In the fruit fly Drosophila, the Reaper (rpr), HeadInvolution Defective (hid) and GRIM proteins physically interact withand inhibit the anti-apoptotic activity of the Drosophila family ofIAPs. In the mammal, the proteins SMAC/DIABLO act to block the IAPs andallow apoptosis to proceed. It was shown that during normal apoptosis,SMAC is processed into an active form and is released from themitochondria into the cytoplasm where it physically binds to IAPs andprevents the IAP from binding to a caspase. This inhibition of the IAPallows the caspase to remain active and thus proceed with apoptosis.Interestingly, sequence homology between the IAP inhibitors shows thatthere is a four amino acid motif in the N-terminus of the processed,active proteins. This tetrapeptide appears to bind into a hydrophobicpocket in the BIR domain and disrupts the BIR domain binding to caspases(Chai et al., (2000) Nature 406:855-862, Liu et al., (2000) Nature408:1004-1008, Wu et al., (2000) Nature 408 1008-1012).

SUMMARY OF THE INVENTION

In one aspect of the present invention there are provided novelinhibitors of IAP proteins having the general formula (I)

wherein

R¹ is C₃₋₇ cycloalkyl,

Ph is phenyl,

R², R³, R⁴, R⁵, and R⁶ are each independently in each occurrence H orC₁₋₆ alkyl; or,

a pharmaceutically acceptable salt thereof.

Formula I includes all stereoisomers.

In another aspect of the invention, there are provided compositionscomprising compounds of formula I and a carrier, diluent or excipient.

In another aspect of the invention, there is provided a method ofinducing apoptosis in a cell comprising introducing into said cell acompound of formula I.

In another aspect of the invention, there is provided a method ofsensitizing a cell to an apoptotic signal comprising introducing intosaid cell a compound of formula I.

In another aspect of the invention, there is provided a method forinhibiting the binding of an IAP protein to a caspase protein comprisingcontacting said IAP protein with a compound of formula I.

In another aspect of the invention, there is provided a method fortreating a disease or condition associated with the overexpression of anIAP protein in a mammal, comprising administering to said mammal aneffective amount of a compound of formula I.

In another aspect of the invention, there is provided a method fortreating cancer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the efficacy of Ia alone, as well as in combination withApomab, along with efficacy data for prior art compound III alone and incombination with Apomab, in the Xenograft Model using Calu-6 lungadenocarcinoma cells. Ia was administered p.o. III was administered i.v.The doses were selected to produce the maximum tolerated dose of thedrug.

FIG. 2 shows the efficacy of Ia alone, as well as in combination withApomab, along with efficacy data for prior art compound III alone and incombination with Apomab, in the Xenograft Model using Colo205 colorectaladenocarcinoma cells. Ia was administered p.o. III was administered i.v.The doses were selected to produce the maximum tolerated dose of thedrug.

The phrase “a” or “an” entity as used herein refers to one or more ofthat entity; for example, a compound refers to one or more compounds orat least one compound. As such, the terms “a” (or “an”), “one or more”,and “at least one” can be used interchangeably herein.

As used in this specification, whether in a transitional phrase or inthe body of the claim, the terms “comprise(s)” and “comprising” are tobe interpreted as having an open-ended meaning. That is, the terms areto be interpreted synonymously with the phrases “having at least” or“including at least”. When used in the context of a process, the term“comprising” means that the process includes at least the recited steps,but may include additional steps. When used in the context of a compoundor composition, the term “comprising” means that the compound orcomposition includes at least the recited features or components, butmay also include additional features or components.

The term “independently” is used herein to indicate that a variable isapplied in any one instance without regard to the presence or absence ofa variable having that same or a different definition within the samecompound. Thus, in a compound in which R″ appears twice and is definedas “independently carbon or nitrogen”, both R″s can be carbon, both R″scan be nitrogen, or one R″ can be carbon and the other nitrogen.

The term “optional” or “optionally” as used herein means that asubsequently described event or circumstance may, but need not, occur,and that the description includes instances where the event orcircumstance occurs and instances in which it does not. For example,“optionally substituted” means that the optionally substituted moietymay incorporate a hydrogen or a substituent.

The term “about” is used herein to mean approximately, in the region of,roughly, or around. When the term “about” is used in conjunction with anumerical range, it modifies that range by extending the boundariesabove and below the numerical values set forth. In general, the term“about” is used herein to modify a numerical value above and below thestated value by a variance of 20%.

As used herein, the recitation of a numerical range for a variable isintended to convey that the invention may be practiced with the variableequal to any of the values within that range. Thus, for a variable whichis inherently discrete, the variable can be equal to any integer valueof the numerical range, including the end-points of the range.Similarly, for a variable which is inherently continuous, the variablecan be equal to any real value of the numerical range, including theend-points of the range. As an example, a variable which is described ashaving values between 0 and 2, can be 0, 1 or 2 for variables which areinherently discrete, and can be 0.0, 0.1, 0.01, 0.001, or any other realvalue for variables which are inherently continuous.

Compounds of formula I exhibit tautomerism. Tautomeric compounds canexist as two or more interconvertable species. Prototropic tautomersresult from the migration of a covalently bonded hydrogen atom betweentwo atoms. Tautomers generally exist in equilibrium and attempts toisolate an individual tautomers usually produce a mixture whose chemicaland physical properties are consistent with a mixture of compounds. Theposition of the equilibrium is dependent on chemical features within themolecule. For example, in many aliphatic aldehydes and ketones, such asacetaldehyde, the keto form predominates while; in phenols, the enolform predominates. Common prototropic tautomers include keto/enol(—C(═O)—CH—⇄—C(—OH)═CH—), amide/imidic acid (—C(═O)—NH—⇄—C(—OH)═N—) andamidine (—C(═NR)—NH—⇄—C(—NHR)═N—) tautomers. The latter two areparticularly common in heteroaryl and heterocyclic rings. The presentinvention encompasses all tautomeric forms of the compounds describedherein.

“Alkyl” means a branched or unbranched saturated aliphatic hydrocarbongroup having up to 6 carbon atoms unless otherwise specified, also whenused as part of another term, for example “alkylamino.” Examples ofpreferred alkyl groups include methyl, ethyl, n-propyl, isopropyl,n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, 2-methylbutyl,2,2-dimethylpropyl, n-hexyl, 2-methylpentyl, 2,2-dimethylbutyl, and thelike. The terms “lower alkyl” “C₁-C₄ alkyl” and “alkyl of 1 to 4 carbonatoms” are synonymous and used interchangeably to mean methyl, ethyl,1-propyl, isopropyl, cyclopropyl, 1-butyl, sec-butyl or t-butyl.

Cycloalkyl groups can be mono-, bi-, or tricyclic aliphatic rings of 3to 7 carbon atoms. Preferred groups include cyclopropyl, cyclobutyl,cyclopentyl and cyclohexyl groups and more preferred are cyclopropyl andcyclohexyl and most preferred is cyclohexyl.

“Amino-protecting group” refers to a derivative of the groups commonlyemployed to block or protect an amino group while reactions are carriedout on other functional groups on the compound. Examples of suchprotecting groups include carbamates, amides, alkyl and aryl groups,imines, as well as many N-heteroatom derivatives which can be removed toregenerate the desired amine group. Preferred amino protecting groupsare Boc, Fmoc and Cbz. Further examples of these groups are found in T.W. Greene and P. G. M. Wuts, “Protective Groups in Organic Synthesis”,2^(nd) ed., John Wiley & Sons, Inc., New York, N.Y., 1991, chapter 7; E.Haslam, “Protective Groups in Organic Chemistry”, J. G. W. McOmie, Ed.,Plenum Press, New York, N.Y., 1973, Chapter 5, and T. W. Greene,“Protective Groups in Organic Synthesis”, John Wiley and Sons, New York,N.Y., 1981. The term “protected amino” refers to an amino groupsubstituted with one of the above amino-protecting groups. These groupscan be used during synthesis.

“Carboxy-protecting group” refers to one of the ester derivatives of thecarboxylic acid group commonly employed to block or protect thecarboxylic acid group while reactions are carried out on otherfunctional groups on the compound. Examples of such carboxylic acidprotecting groups include 4-nitrobenzyl, 4-methoxybenzyl,3,4-dimethoxybenzyl, 2,4-dimethoxybenzyl, 2,4,6-trimethoxybenzyl,2,4,6-trimethylbenzyl, pentamethylbenzyl, 3,4-methylenedioxybenzyl,benzhydryl, 4,4′-dimethoxybenzhydryl, 2,2′,4,4′-tetramethoxybenzhydryl,alkyl such as t-butyl or t-amyl, trityl, 4-methoxytrityl,4,4′-dimethoxytrityl, 4,4′,4″-trimethoxytrityl, 2-phenylprop-2-yl,trimethylsilyl, t-butyldimethylsilyl, phenacyl, 2,2,2-trichloroethyl,beta-(trimethylsilyl)ethyl, beta-(di(n-butyl)methylsilyl)ethyl,p-toluenesulfonylethyl, 4-nitrobenzylsulfonylethyl, allyl, cinnamyl,1-(trimethylsilylmethyl)prop-1-en-3-yl, and like moieties. The speciesof carboxy-protecting group employed is not critical so long as thederivatized carboxylic acid is stable to the condition of subsequentreaction(s) on other positions of the molecule and can be removed at theappropriate point without disrupting the remainder of the molecule. Inparticular, it is important not to subject a carboxy-protected moleculeto strong nucleophilic bases, such as lithium hydroxide or NaOH, orreductive conditions employing highly activated metal hydrides such asLiAlH₄. (Such harsh removal conditions are also to be avoided whenremoving amino-protecting groups and hydroxy-protecting groups.Preferred carboxylic acid protecting groups are the alkyl (e.g. methyl,ethyl, t-butyl), allyl, benzyl and p-nitrobenzyl groups. Similarcarboxy-protecting groups used in the cephalosporin, penicillin andpeptide arts can also be used to protect a carboxy group substituents.Further examples of these groups are found in T. W. Greene and P. G. M.Wuts, “Protective Groups in Organic Synthesis”, 2^(nd) ed., John Wiley &Sons, Inc., New York, N.Y., 1991, chapter 5; E. Haslam, “ProtectiveGroups in Organic Chemistry”, J. G. W. McOmie, Ed., Plenum Press, NewYork, N.Y., 1973, Chapter 5, and T. W. Greene, “Protective Groups inOrganic Synthesis”, John Wiley and Sons, New York, N.Y., 1981, Chapter5. The term “protected carboxy” refers to a carboxy group substitutedwith one of the above carboxy-protecting groups. These groups can beused during synthesis.

“Hydroxy-protecting group” refers to a derivative of the hydroxy groupcommonly employed to block or protect the hydroxy group while reactionsare carried out on other functional groups on the compound. Examples ofsuch protecting groups include tetrahydropyranyloxy, benzoyl, acetoxy,carbamoyloxy, benzyl, and silylethers (e.g. TBS, TBDPS) groups. Furtherexamples of these groups are found in T. W. Greene and P. G. M. Wuts,“Protective Groups in Organic Synthesis”, 2^(nd) ed., John Wiley & Sons,Inc., New York, N.Y., 1991, chapters 2-3; E. Haslam, “Protective Groupsin Organic Chemistry”, J. G. W. McOmie, Ed., Plenum Press, New York,N.Y., 1973, Chapter 5, and T. W. Greene, “Protective Groups in OrganicSynthesis”, John Wiley and Sons, New York, N.Y., 1981. The term“protected hydroxy” refers to a hydroxy group substituted with one ofthe above hydroxy-protecting groups. These groups can be used duringsynthesis.

“Inhibitor” means a compound which reduces or prevents the binding ofIAP proteins to caspase proteins or which reduces or prevents theinhibition of apoptosis by an IAP protein (e.g., c-IAP-1, c-IAP2, X-IAPor ML-IAP). Alternatively, “inhibitor” means a compound which preventsthe binding interaction of X-IAP with caspases or the bindinginteraction of ML-IAP with SMAC.

“Pharmaceutically acceptable salts” include both acid and base additionsalts. “Pharmaceutically acceptable acid addition salt” refers to thosesalts which retain the biological effectiveness and properties of thefree bases and which are not biologically or otherwise undesirable,formed with inorganic acids such as hydrochloric acid, hydrobromic acid,sulfuric acid, nitric acid, carbonic acid, phosphoric acid and the like,and organic acids may be selected from aliphatic, cycloaliphatic,aromatic, araliphatic, heterocyclic, carboxylic, and sulfonic classes oforganic acids such as formic acid, acetic acid, propionic acid, glycolicacid, gluconic acid, lactic acid, pyruvic acid, oxalic acid, malic acid,maleic acid, maloneic acid, succinic acid, fumaric acid, tartaric acid,citric acid, aspartic acid, ascorbic acid, glutamic acid, anthranilicacid, benzoic acid, cinnamic acid, mandelic acid, embonic acid,phenylacetic acid, methanesulfonic acid, ethanesulfonic acid,p-toluenesulfonic acid, salicyclic acid and the like.“Pharmaceuticallyacceptable base addition salts” include those derived from inorganicbases such as sodium, potassium, lithium, ammonium, calcium, magnesium,iron, zinc, copper, manganese, aluminum salts and the like. Particularlypreferred are the ammonium, potassium, sodium, calcium and magnesiumsalts. Salts derived from pharmaceutically acceptable organic nontoxicbases includes salts of primary, secondary, and tertiary amines,substituted amines including naturally occurring substituted amines,cyclic amines and basic ion exchange resins, such as isopropylamine,trimethylamine, diethylamine, triethylamine, tripropylamine,ethanolamine, 2-diethylaminoethanol, trimethamine, dicyclohexylamine,lysine, arginine, histidine, caffeine, procaine, hydrabamine, choline,betaine, ethylenediamine, glucosamine, methylglucamine, theobromine,purines, piperizine, piperidine, N-ethylpiperidine, polyamine resins andthe like. Particularly preferred organic non-toxic bases areisopropylamine, diethylamine, ethanolamine, trimethamine,dicyclohexylamine, choline, and caffeine. Formula I is also intended toencompass hydrates and solvates of the compounds.

The present invention provides novel compounds having the generalformula I,

In a specific embodiment, R¹ is cyclohexyl. In another specificembodiment, R¹ is cyclopentyl. In a particular embodiment, R¹ isoriented such that the amino acid, or amino acid analogue, which itcomprises is in the L-configuration.

R² and R³ are independently H or C₁₋₆ alkyl. In one embodiment R² and R³are both H. In another embodiment R² is methyl and R³ is H.

R⁴ is H or C₁₋₆ alkyl. In a specific embodiment R⁴ is H or methyl. Inanother embodiment R⁴ is methyl. In another embodiment R⁴ is orientedsuch that the amino acid, or amino acid analogue, which it comprises isin the L-configuration.

R⁵ and R⁶ are each independently H or C₁₋₆ alkyl. In one embodiment, R⁵and R⁶ are H or methyl. In one embodiment, R⁵ is H and R⁶ is methyl. Inanother embodiment, R⁵ is methyl and R⁶ is H. In another embodiment R⁵and R⁶ are both methyl. In another embodiment, R⁵ and R⁶ are both H.

In another aspect of the present invention the compound according toformula I is(S)-1-[(S)-2-cyclohexyl-2-((S)-2-methylamino-propionylamino)-acetyl]-pyrrolidine-2-carboxylicacid (2-oxazol-2-yl-4-phenyl-thiazol-5-yl)-amide (Ia).

Compounds of the invention contain one or more asymmetric carbon atoms.Accordingly, the compounds may exist as stereoisomers, includingdiastereomers, enantiomers or mixtures thereof. The syntheses of thecompounds may employ racemates, diastereomers or enantiomers as startingmaterials or as intermediates. Diastereomeric compounds may be separatedby chromatographic or crystallization methods. Similarly, enantiomericmixtures may be separated using the same techniques or others known inthe art. Each of the asymmetric carbon atoms may be in the R or Sconfiguration and both of these configurations are within the scope ofthe invention. Preferably, compounds of the invention have the followingstereochemical configuration of formula Ib wherein R¹, R², R³, R⁴, R⁵and R⁶ are as described herein.

Compounds of formula II wherein A is an optionally substituted 5-memberheterocycle comprising 1 to 4 heteroatoms have been disclosed in USPublication No. 20060014700. In some compounds disclosed in thispublication A is N-(4-phenylthiazol-5-yl).

It has now been found that compounds wherein A is2-(oxazol-2-yl)-4-phenylthiazol-5-yl per the invention afford anunexpected increase in potency and oral bioavailabilty. In addition, thecompounds of the invention have generally lower side effects, includingimproved lung toxicity, e.g., compared to compound III a compounddisclosed in US Publication No. 20060014700. FIGS. 1 and 2 show acomparative activity in xenograft tumor models between iv administrationof III, compared to compound Ia of the present invention administeredorally.

Synthesis

Compounds of the invention are prepared using standard organic synthetictechniques from commercially available starting materials and reagents.General techniques are disclosed in WO 98/46576 and U.S. Pat. No.7,244,851, which are incorporated by reference herein for thepreparation methods disclosed therein. It will be appreciated thatsynthetic procedures employed in the preparation of compounds of theinvention will depend on the particular substituents present in acompound and that various protection and deprotection may be required asis standard in organic synthesis. In a general synthetic schemecompounds of the invention may be prepared using typical peptidechemistry techniques by coupling the amino acid residue analogues withtypical amide coupling procedures. In scheme 1, amine-protected aminoacid residue analogues are coupled and deprotected sequentially to givethe final compounds using peptide synthesis protocols.

It will be appreciated that the amino acid analogs may be coupled in anyorder and may be prepared using solid phase support which is routine inthe art.

When compounds of the invention incorporate R² or R³ substituents otherthan H, they may also be prepared by substitution of a suitable acidintermediate which incorporates a leaving group with a desired amine.For example Br—CH(R⁴)—C(O)—OH is substituted with an amine R²—NH₂ orR²—NH—R³ according to scheme 2.

Alternatively, the substitution reaction introducing R² or R³substituents may be performed as a final step in the preparation of thecompound as illustrated in scheme 3.

In a particular embodiment, 2-bromopropionic acid is reacted with theappropriate amines dissolved in DMF and bubbled until substitution iscomplete to form N-substituted alanine residue.

Amine substituted ring A compounds which serve as an intermediate forpreparing compounds of the invention are commercially available or elseare prepared from commercially available reagents employing standardorganic chemistry techniques. 2-(Oxazol-2-yl)-4-phenylthiazol-5-aminecan be prepared by condensation of an α-aminophenylacetonitrilehydrochloride and oxazole-2-carbaldehyde in the presence of sulfur andTEA (Scheme 4).

Utility

The compounds of the invention inhibit the binding of IAP proteins tocaspases, in particular X-IAP binding interaction with caspases 3 and 7.The compounds also inhibit the binding of ML-IAP to Smac protein.Accordingly, the compounds of the invention are useful for inducingapoptosis in cells or sensitizing cells to apoptotic signals, inparticular cancer cells. Compounds of the invention are useful forinducing apoptosis in cells that overexpress IAP proteins (e.g., c-IAP1,c-IAP2, X-IAP or ML-IAP). Alternatively, compounds of the invention areuseful for inducing apoptosis in cells in which the mitochondrialapoptotic pathway is disrupted such that release of Smac from ML-IAPproteins is inhibited, for example by up regulation of Bcl-2 or downregulation of Bax/Bak. More broadly, the compounds can be used for thetreatment of cancer.

They are especially useful for the treatment of all cancer types whichfail to undergo apoptosis. Examples of such cancer types includeneuroblastoma, intestine carcinoma such as rectum carcinoma, coloncarcinoma, familiary adenomatous polyposis carcinoma and hereditarynon-polyposis colorectal cancer, esophageal carcinoma, labial carcinoma,larynx carcinoma, hypopharynx carcinoma, tong carcinoma, salivary glandcarcinoma, gastric carcinoma, adenocarcinoma, medullary thyroidcarcinoma, papillary thyroid carcinoma, renal carcinoma, kidneyparenchym carcinoma, ovarian carcinoma, cervix carcinoma, uterine corpuscarcinoma, endometrium carcinoma, chorion carcinoma, pancreaticcarcinoma, prostate carcinoma, testis carcinoma, breast carcinoma,urinary carcinoma, melanoma, brain tumors such as glioblastoma,astrocytoma, meningioma, medulloblastoma and peripheral neuroectodermaltumors, Hodgkin lymphoma, non-Hodgkin lymphoma, Burkitt lymphoma, acutelymphatic leukemia (ALL), chronic lymphatic leukemia (CLL), acutemyeloid leukemia (AML), chronic myeloid leukemia (CML), adult T-cellleukemia lymphoma, hepatocellular carcinoma, gall bladder carcinoma,bronchial carcinoma, small cell lung carcinoma, non-small cell lungcarcinoma, multiple myeloma, basalioma, teratoma, retinoblastoma,choroidea melanoma, seminoma, rhabdomyo sarcoma, craniopharyngeoma,osteosarcoma, chondrosarcoma, myosarcoma, liposarcoma, fibrosarcoma,Ewing sarcoma and plasmocytoma. Useful is treatment of solid tumors.Useful also is treatment of breast cancer, pancreatic adenocarcinoma ormalignant melanoma.

Compounds of the invention are useful for sensitizing cells to apoptoticsignals. Accordingly, the compounds may be administered prior to,concomitantly with, or following administration of radiation therapy orcytostatic or antineoplastic chemotherapy. Suitable cytostaticchemotherapy compounds include, but are not limited to (i)antimetabolites, such as cytarabine, fludarabine,5-fluoro-2′-deoxyuiridine, gemcitabine, hydroxyurea or methotrexate;(ii) DNA-fragmenting agents, such as bleomycin, (iii) DNA-crosslinkingagents, such as chlorambucil, cisplatin, cyclophosphamide or nitrogenmustard; (iv) intercalating agents such as adriamycin (doxorubicin) ormitoxantrone; (v) protein synthesis inhibitors, such as L-asparaginase,cycloheximide, puromycin or diphtheria toxin; (Vi) topoisomerase Ipoisons, such as camptothecin or topotecan; (vii) topoisomerase IIpoisons, such as etoposide (VP-16) or teniposide; (viii)microtubule-directed agents, such as colcemid, colchicine, paclitaxel,vinblastine or vincristine; (ix) kinase inhibitors such as flavopiridol,staurosporin, STI571 (CPG 57148B) or UCN-01 (7-hydroxystaurosporine);(x) miscellaneous investigational agents such as thioplatin, PS-341,phenylbutyrate, ET-18-OCH₃, or farnesyl transferase inhibitors(L-739749, L-744832); polyphenols such as quercetin, resveratrol,piceatannol, epigallocatechine gallate, theaflavins, flavanols,procyanidins, betulinic acid and derivatives thereof; (xi) hormones suchas glucocorticoids or fenretinide; (xii) hormone antagonists, such astamoxifen, finasteride or LHRH antagonists. In a preferred embodiment,compounds of the present invention are coadministered with a cytostaticcompound selected from the group consisting of cisplatin, doxorubicin,paclitaxel, docetaxel and mitomycin C. Most preferred, the cytostaticcompound is doxorubicin. Useful are combinations with 5-FU, gemcitabine,capecitabine, vinorelbine, bevacizumab, or taxanes.

Another class of active compounds which can be used in the presentinvention are those which are able to sensitize for or induce apoptosisby binding to death receptors (“death receptor agonists”). Such agonistsof death receptors include death receptor ligands such as tumor necrosisfactor α (TNF-α), tumor necrosis factor β (TNF-β, lymphotoxin-α), LT-β(lymphotoxin-β), TRAIL (Apo2L, DR4 ligand), CD95 (Fas, APO-1) ligand,TRAMP (DR3, Apo-3) ligand, DR6 ligand as well as fragments andderivatives of any of said ligands. Preferably, the death receptorligand is TNF-α. More preferably the death receptor ligand isApo2L/TRAIL. Furthermore, death receptors agonists comprise agonisticantibodies to death receptors such as anti-CD95 antibody, anti-TRAIL-R1(DR4) antibody, anti-TRAIL-R2 (DR5) antibody, anti-TRAIL-R3 antibody,anti-TRAIL-R4 antibody, anti-DR6 antibody, anti-TNF-R1 antibody andanti-TRAMP (DR3) antibody as well as fragments and derivatives of any ofsaid antibodies.

For the purpose of sensitizing cells for apoptosis, the compounds of thepresent invention can be also used in combination with radiationtherapy. The phrase “radiation therapy” refers to the use ofelectromagnetic or particulate radiation in the treatment of neoplasia.Radiation therapy is based on the principle that high-dose radiationdelivered to a target area will result in the death of reproducing cellsin both tumor and normal tissues. The radiation dosage regimen isgenerally defined in terms of radiation absorbed dose (rad), time andfractionation, and must be carefully defined by the oncologist. Theamount of radiation a patient receives will depend on variousconsideration but the two most important considerations are the locationof the tumor in relation to other critical structures or organs of thebody, and the extent to which the tumor has spread. Examples ofradiotherapeutic agents are provided in, but not limited to, radiationtherapy and is known in the art (Hellman, Principles of RadiationTherapy, Cancer, in Principles I and Practice of Oncology, 24875 (Devitaet al., 4th ed., vol 1, 1993). Recent advances in radiation therapyinclude three-dimensional conformal external beam radiation, intensitymodulated radiation therapy (IMRT), stereotactic radiosurgery andbrachytherapy (interstitial radiation therapy), the latter placing thesource of radiation directly into the tumor as implanted “seeds”. Thesenewer treatment modalities deliver greater doses of radiation to thetumor, which accounts for their increased effectiveness when compared tostandard external beam radiation therapy.

Ionizing radiation with beta-emitting radionuclides is considered themost useful for radiotherapeutic applications because of the moderatelinear energy transfer (LET) of the ionizing particle (electron) and itsintermediate range (typically several millimeters in tissue). Gamma raysdeliver dosage at lower levels over much greater distances. Alphaparticles represent the other extreme, they deliver very high LETdosage, but have an extremely limited range and must, therefore, be inintimate contact with the cells of the tissue to be treated. Inaddition, alpha emitters are generally heavy metals, which limits thepossible chemistry and presents undue hazards from leakage ofradionuclide from the area to be treated. Depending on the tumor to betreated all kinds of emitters are conceivable within the scope of thepresent invention.

Furthermore, the present invention encompasses types of non-ionizingradiation like e.g.

ultraviolet (UV) radiation, high energy visible light, microwaveradiation (hyperthermia therapy), infrared (IR) radiation and lasers. Ina particular embodiment of the present invention UV radiation isapplied.

More generally, the compounds of the invention can be used incombination therapy. “Combination therapy” includes the administrationof the subject compounds in further combination with other biologicallyactive ingredients (such as, but not limited to, a second and differentantineoplastic agent) and non-drug therapies (such as, but not limitedto, surgery or radiation treatment). For instance, the compounds of theinvention can be used in combination with other pharmaceutically activecompounds, preferably compounds that are able to enhance the effect ofthe compounds of the invention. The compounds of the invention can beadministered simultaneously (as a single preparation or separatepreparation) or sequentially to the other drug therapy. In general, acombination therapy envisions administration of two or more drugs duringa single cycle or course of therapy.

Thus, in one aspect of the invention, the subject compounds may beadministered in combination with one or more separate agents thatmodulate protein kinases involved in various disease states or targetsdownstream thereof. Examples of such kinases may include, but are notlimited to: serine/threonine specific kinases, receptor tyrosinespecific kinases and non-receptor tyrosine specific kinases.Serine/threonine kinases include mitogen activated protein kinases(MAPK), meiosis specific kinase (MEK), RAF and aurora kinase. Examplesof receptor kinase families include epidermal growth factor receptor(EGFR) (e.g. HER2/neu, HER3, HER4, ErbB, ErbB2, ErbB3, ErbB4, Xmrk, DER,Let23); fibroblast growth factor (FGF) receptor (e.g.FGF-R1,GFF-R2/BEK/CEK3, FGF-R3/CEK2, FGF-R4/TKF, KGF-R); hepatocytegrowth/scatter factor receptor (HGFR) (e.g, MET, RON, SEA, SEX); insulinreceptor (e.g. IGFI-R, PI3K, AKT, mTor); Eph (e.g. CEK5, CEK8, EBK, ECK,EEK, EHK-1, EHK-2, ELK, EPH, ERK, HEK, MDK2, MDK5, SEK); Axl (e.g.Mer/Nyk, Rse); RET; and platelet-derived growth factor receptor (PDGFR)(e.g. PDGFα-R, PDGβ-R, CSF1-R/FMS, SCF-R/C-KIT, VEGF-R/FLT, NEK/FLK1,FLT3/FLK2/STK-1). Non-receptor tyrosine kinase families include, but arenot limited to, BCR-ABL (e.g. p43^(abl), ARG); BTK (e.g. ITK/EMT, TEC);CSK, FAK, FPS, JAK, SRC, BMX, FER, CDK and SYK.

In another aspect of the invention, the subject compounds may beadministered in combination with one or more separate agents thatmodulate non-kinase biological targets or processes. Such targetsinclude histone deacetylases (HDAC), DNA methyltransferase (DNMT), heatshock proteins (e.g. HSP90), hedgehog inhibitors and proteosomes.

In a preferred embodiment, subject compounds may be combined withantineoplastic agents (e.g. small molecules, monoclonal antibodies,antisense RNA, and fusion proteins) that inhibit one or more biologicaltargets such as Erivedge, Zolinza, Tarceva, Iressa, Tykerb, Gleevec,Sutent, Sprycel, Nexavar, CNF2024, RG108, BMS387032, Affinitak, Avastin,Herceptin, Erbitux, AG24322, PD325901, ZD6474, PD184322, Obatodax,ABT737 and AEE788. Also included are monoclonal antibodies directedtoward specific kinases and/or receptors, e.g., those mentioned hereinand others. Such combinations may enhance therapeutic efficacy overefficacy achieved by any of the agents alone and may prevent or delaythe appearance of resistant mutational variants.

In certain preferred embodiments, the compounds of the invention areadministered in combination with a chemotherapeutic agent.Chemotherapeutic agents encompass a wide range of therapeutic treatmentsin the field of oncology. These agents are administered at variousstages of the disease for the purposes of shrinking tumors, destroyingremaining cancer cells left over after surgery, inducing remission,maintaining remission and/or alleviating symptoms relating to the canceror its treatment. Examples of such agents (some of which are alsodiscussed above) include, but are not limited to, alkylating agents suchas mustard gas derivatives (Mechlorethamine, cylophosphamide,chlorambucil, melphalan, ifosfamide), ethylenimines (thiotepa,hexamethylmelanine), Alkylsulfonates (Busulfan), Hydrazines andTriazines (Altretamine, Procarbazine, Dacarbazine and Temozolomide),Nitrosoureas (Carmustine, Lomustine and Streptozocin), Ifosfamide andmetal salts (Carboplatin, Cisplatin, and Oxaliplatin); plant alkaloidssuch as Podophyllotoxins (Etoposide and Tenisopide), Taxanes (Paclitaxeland Docetaxel), Vinca alkaloids (Vincristine, Vinblastine, Vindesine andVinorelbine), and Camptothecan analogs (Irinotecan and Topotecan);anti-tumor antibiotics such as Chromomycins (Dactinomycin andPlicamycin), Anthracyclines (Doxorubicin, Daunorubicin, Epirubicin,Mitoxantrone, Valrubicin and Idarubicin), and miscellaneous antibioticssuch as Mitomycin, Actinomycin and Bleomycin; anti-metabolites such asfolic acid antagonists (Methotrexate, Pemetrexed, Raltitrexed,Aminopterin), pyrimidine antagonists (5-Fluorouracil, Floxuridine,Cytarabine, Capecitabine, and Gemcitabine), purine antagonists(6-Mercaptopurine and 6-Thioguanine) and adenosine deaminase inhibitors(Cladribine, Fludarabine, Mercaptopurine, Clofarabine, Thioguanine,Nelarabine and Pentostatin); topoisomerase inhibitors such astopoisomerase I inhibitors (Ironotecan, topotecan) and topoisomerase IIinhibitors (Amsacrine, etoposide, etoposide phosphate, teniposide);monoclonal antibodies (Alemtuzumab, Gemtuzumabozogamicin, Rituximab,Trastuzumab, IbritumomabTioxetan, Cetuximab, Panitumumab, Tositumomab,Bevacizumab); and miscellaneous anti-neoplastics such as ribonucleotidereductase inhibitors (Hydroxyurea); adrenocortical steroid inhibitor(Mitotane); enzymes (Asparaginase and Pegaspargase); anti-microtubuleagents (Estramustine); and retinoids (Bexarotene, Isotretinoin,Tretinoin (ATRA), etc.

The invention also includes pharmaceutical compositions or medicamentscontaining the compounds of the invention and a therapeutically inertcarrier, diluent or excipient, as well as methods of using the compoundsof the invention to prepare such compositions and medicaments.Typically, the compounds of formula I used in the methods of theinvention are formulated by mixing at ambient temperature at theappropriate pH, and at the desired degree of purity, withphysiologically acceptable carriers, i.e., carriers that are non-toxicto recipients at the dosages and concentrations employed into agalenical administration form. The pH of the formulation depends mainlyon the particular use and the concentration of compound, but preferablyranges anywhere from about 3 to about 8. Formulation in an acetatebuffer at pH 5 is a suitable embodiment.

The inhibitory compound for use herein is preferably sterile. Thecompound ordinarily will be stored as a solid composition, althoughlyophilized formulations or aqueous solutions are acceptable.

The composition of the invention will be formulated, dosed, andadministered in a fashion consistent with good medical practice. Factorsfor consideration in this context include the particular disorder beingtreated, the particular mammal being treated, the clinical condition ofthe individual patient, the cause of the disorder, the site of deliveryof the agent, the method of administration, the scheduling ofadministration, and other factors known to medical practitioners. The“effective amount” of the compound to be administered will be governedby such considerations, and is the minimum amount necessary to treat thetarget diseases, e.g., to inhibit IAP interaction with caspases, induceapoptosis or sensitize a malignant cell to an apoptotic signal. Suchamount is preferably below the amount that is toxic to normal cells, orthe mammal as a whole.

Generally, the compounds of this invention can be dosed once or multipletimes daily. They can also be dosed on a continuous daily schedulewithout treatment breaks. They can also be thus dosed with treatmentbreaks. These options are also available when used with other agents ormodalities. The initial pharmaceutically effective amount of thecompound of the invention administered parenterally per dose will be inthe range of about 0.01-100 mg/kg, preferably about 0.1 to 20 mg/kg ofpatient body weight per day, with the typical initial range of compoundused being 0.3 to 15 mg/kg/day. Oral unit dosage forms, such as tabletsand capsules, preferably contain from about 25 to about 1000 mg of thecompound of the invention. Oral administration is preferred. On/Offdosing schedules can be used as are common for cancer treatments, e.g.,daily oral dosing for 1, 2, 3, 4, etc., weeks, followed by a treatmentbreak of 1, 2, etc., weeks, followed by daily oral dosing for 1, 2, 3,4, etc., weeks, etc. In a preferred option, the compounds of theinvention are dosed daily in a range of about 25 to about 3000 mg perday, more preferably about 300 to about 1500 mg of compound per day.

The compound of the invention may be administered by any suitable means,including oral, topical, transdermal, parenteral, subcutaneous,intraperitoneal, intrapulmonary, and intranasal, and, if desired forlocal treatment, intralesional administration. Parenteral infusionsinclude intramuscular, intravenous, intraarterial, intraperitoneal, orsubcutaneous administration. An example of a suitable oral dosage formis a tablet containing about 25 mg, 50 mg, 100 mg, 250 mg, or 500 mg ofthe compound of the invention compounded with about 90-30 mg anhydrouslactose, about 5-40 mg sodium croscarmellose, about 5-30 mgpolyvinylpyrrolidone (PVP) K30, and about 1-10 mg magnesium stearate.The powdered ingredients are first mixed together and then mixed with asolution of the PVP. The resulting composition can be dried, granulated,mixed with the magnesium stearate and compressed to tablet form usingconventional equipment. An aerosol formulation can be prepared bydissolving the compound, for example 5-400 mg, of the invention in asuitable buffer solution, e.g. a phosphate buffer, adding a tonicifier,e.g. a salt such sodium chloride, if desired. The solution is typicallyfiltered, e.g. using a 0.2 micron filter, to remove impurities andcontaminants.

More generally, the compounds of this invention can be used inaccordance with the disclosure given in WO 98/46576 and U.S. Pat. No.7,244,851, whose disclosures are incorporated by reference herein fortheir general guidance on how to use the compounds.

EXAMPLES

The invention will be more fully understood by reference to thefollowing examples. They should not, however, be construed as limitingthe scope of the invention. Abbreviations used herein are as follows:

ACN: acetonitrile;

Chg: cyclohexylglycine;

DCM: dichloromethane

DIPEA: diisopropylethylamine;

DMAP: 4-dimethylaminopyridine;

DME: 1,2-dimethoxyethane;

DMF: dimethylformamide;

DMSO: dimethylsulfoxide

EDC: 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide;

EEDQ: 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline

LCMS: liquid chromatography mass spectrometry;

HATU: O-(7-Azobenzotriazol-1-yl)-1,1,3,3-tetramethyluroniumhexafluorophosphate;

HOBt: N-Hydroxybenzotriazole

HBTU: 2-(1H-Benzotriazol-1-yl)-1,1,3,3-Tetramethyl-uroniumHexafluorophosphate

HPLC: high performance liquid chromatography;

NBS: N-bromosuccinamide;

TASF: tris(dimethylamino)sulfonium difluorotrimethylsilicate;

TEA: triethylamine;

TFA: trifluoroacetate;

THF: tetrahydrofuran;

Referential Example 11-[2-Cyclohexyl-2-(2-methylamino-propionylamino)-acetyl]-pyrrolidine-2-carboxylicacid (2-phenyl-2H-pyrazol-3-yl)-amide

A solution of Boc-MeAla-Chg-Pro-OH (47.0 mg, 0.107 mmol) and pyridine(26 μL, 0.32 mmol) in anhydrous dichloromethane (300 μL) was cooled to0° C. and a solution of oxalyl chloride in dichloromethane (54 μL, 2.0M, 0.11 mmol) was added dropwise over 10 minutes. The mixture wasstirred at 0° C. for 15 minutes, then at ambient temperature for 45minutes, and a solution of 5-amino-1-phenylpyrazole (15.9 mg, 0.100mmol; TCI America catalog #A0174) and pyridine (15.5 μL, 0.191 mmol) indichloromethane (0.5 mL) was added. The resulting mixture was stirred atambient temperature for 16 hours, diluted with dichloromethane to 20 mL,and washed with 0.2 N aqueous sodium hydroxide (20 mL). The organicphase was dried (MgSO₄) and concentrated under reduced pressure. Thecrude product was purified by column chromatography (silica gel, 60%ethyl acetate in hexanes, then 100% ethyl acetate) to yield a yellowoil: m/z 581 (M+H⁺). The oil was treated with 5% trifluoroacetic acid indichloromethane (2 mL), and after 18 hours the solvent was removed invacuo. The resulting oil (29.3 mg, 57% yield over 2 steps) was furtherpurified by reversed-phase HPLC to yield the product (TFA salt, 9.6 mg,15% yield): m/z 481 (M+H⁺), 503 (M+Na⁺).

Referential Example 2 Acid Fluoride Coupling Procedure

A solution of Boc-MeAla-Chg-Pro-OH (2.3 mmol) and pyridine (6.9 umol) inanhydrous DCM (23 ml) was cooled to 0° C. and cyanuric fluoride (2.3mmol) added dropwise over 30 sec. The mixture was stirred at 0° C. for15 min, at RT for 5 h, and then quenched with water. The mixture wasextracted three times with DCM (total 100 ml), and the combined organicphases washed with brine and dried (Na₂SO₄). Filtration andconcentration in vacuo yielded the peptide acid fluoride as a clear,colorless oil used directly without further purification.

A solution of the crude acid fluoride (0.50 mmol) and pyridine (1.5mmol) in DCM (2.5 ml) was added to the solid amine (14, 0.50 mmol), andthe resulting mixture stirred either at RT or at 50° C. (sealed vessel).The mixture was poured into aqueous NaHCO₃ and then extracted threetimes with dichloromethane (total 100 ml). The combined organic phaseswere washed with brine, dried (Na₂SO₄), filtered and concentrated invacuo. The crude peptide amide was used directly without furtherpurification.

Referential Example 31-[2-Cyclohexyl-2-(2-methylamino-propionylamino)-acetyl]-pyrrolidine-2-carboxylicacid (4-phenyl-[1,2,3]thiadiazol-5-yl)-amide

step 1: To a solution of Boc-L-Pro-OH (2 eq), HOBt (1.9 eq), EDC-HCl(1.9 eq) and DIPEA (5 eq) in DMF (10-15 vol) was added4-phenyl-1,2,3-thiadiazol-5-amine (16). The reaction, initially mildyexothermic, was heated to 75° C. and stirred overnight, cooled to RT andthe DMF was partially removed in vacuo. The solution was diluted withEtOAc (10-15 vol) followed by washing with 1M HCl (2×), NaHCO₃ (1×), andbrine (1×) (1:1 aq/org). The organic layer was concentrated in vacuo andthe resulting solid was slurried in refluxing MeCN (a minimum volumenecessary for easy stirring) for 30 min and then cooled to RT. Suctionfiltration gave Boc-protected conjugation product as an off-whitecrystalline solid in ca. 77% yield. The Boc-protected product wassuspended in a solution of 4M HCl/dioxane (4-5 eq acid) and MeCN (1 voleq to the dioxane solution) and stirred at RT until LCMS indicatedcomplete deprotection (ca. 1 h). The reaction mixture was concentratedin vacuo and the resulting solid was vigorously slurried in refluxingMeCN (a minimum volume necessary for easy stirring), cooled to RT, andthe solid collected by suction filtration and washed with cold MeCNuntil residual color was removed from the cake which afforded the HClsalt of (S)—N-(4-phenyl-1,2,3-thiadiazol-5-yl)pyrrolidine-2-carboxamide(17) as an off-white solid in approximately quantitative yield.

step 2: To a solution of 17 and DIPEA (5 eq) in DMF (10-15 vol) wasadded the Boc-L-Chg (1.5 eq), HOBt (1.4 eq) and EDC-HCl (1.4 eq). Thereaction was stirred for ca 2 h then diluted with EtOAc (15 vol) andwashed with 1M HCl (2×), NaHCO₃ (1×), and brine (1×) (1:1 aq/org). Theorganic extract was dried (Na₂SO₄), filtered and concentrated in vacuo.The resulting solid is slurried in EtOH/Hexane (20:80) (a minimum volumenecessary for easy stirring) and filtered to give Boc-protectedconjugate product as a fluffy white solid in ca. 80% yield. TheBoc-protected was dissolved in a solution of 4M HCl/dioxane (4-5 eqacid) and MeCN (0.25 volume eq to the dioxane solution) and stirred atRT for ca. 1 hr. The reaction was concentrated to dryness with toluene(2×) (the same volume as the deprotection solution) to yield the HClsalt of(S)-1-((S)-2-amino-2-cyclohexylacetyl)-N-(4-phenyl-1,2,3-thiadiazol-5-yl)pyrrolidine-2-carboxamide(18) as a white crystalline solid in approximately quantitative yield.

step 3: To a solution of 18 and DIPEA (5 eq.) in DMF (10-15 vol) wasadded the Boc-L-N-methyl Ala (1.5 eq), HOBt (1.4 eq), and EDC-HCl (1.4eq). The reaction was stirred for 1 h, diluted with EtOAc (15 vol) andwashed with 1M HCl (2×), NaHCO₃ (1×), and brine (1×) (1:1 aq/org). Theorganic extract was dried (Na₂SO₄), filtered and concentrated in vacuoto give afford Boc-protected conjugate product as a beige, foamy solidin ca. 85% yield. The Boc-protected product was dissolved in a solutionof 4M HCl/dioxane (4-5 eq acid) and MeCN (0.25 volume eq to the dioxanesolution) and stirred at RT for ca. 1 hr. The reaction was concentratedto dryness with toluene (2×) (same volume as deprotection solution) andthe resulting solid was slurried in a solution of MTBE/EtOAc (70:30)(minimal volume necessary for easy stirring), filtered and collected toyield crude(S)-1-((S)-2-cyclohexyl-2-((S)-2-(methylamino)propanamido)acetyl)-N-(4-phenyl-1,2,3-thiadiazol-5-yl)pyrrolidine-2-carboxamide(d) as an off-white free-flowing solid. The crude HCl salt was suspendedin MeOH (4 vol minimum) and dissolved with stirring at 65° C. Warmisopropyl acetate (6-8 vol) was added in two portions, keeping thetemperature at ca. 60° C. then the solution was allowed to cool withstirring. Crystallization took place rapidly, the suspension was stirredat RT for several hours, then stirred at 0° C. for an hour before thesolid was collected by suction filtration. The crude product was washedwith MeOH/iPrOAc (1:4, 2 vol) and dried to 19 as a white/off-whitecrystalline solid in ca. 80% yield.

Referential Example 4 5-Amino-2-(oxazol-2-yl)-4-phenylthiazole

A suspension of α-aminophenylacetonitrile hydrochloride (1.52 g, 8.99mmol), powdered sulfur (289 mg, 9.01 mmol) and oxazole-2-carbaldehyde(873 mg, 8.99 mmol) in EtOH (18 mL) was treated with TEA (1.88 mL, 13.5mmol), and the mixture stirred at 50° C. for 60 min. The cooled mixturewas treated with aqueous hydroxylamine (1.00 ml, 50% wt, 15 mmol) at RTovernight, filtered and concentrated in vacuo. The residue waspartitioned between EtOAc and aqueous NaHCO₃, and the separated organicphase washed with brine, dried (Na₂SO₄), filtered and concentrated invacuo to a dark brown oil. The crude oil was preabsorbed onto SiO₂ andpurified by automated flash chromatography eluting with a gradient of5-70% ethyl acetate in hexanes to yield5-amino-2-(oxazol-2-yl)-4-phenylthiazole (20, 159 mg, 7.3%).

Example 1(S)-1-[(S)-2-Cyclohexyl-2-((S)-2-methylamino-propionylamino)-acetyl]-pyrrolidine-2-carboxylicacid (2-oxazol-2-yl-4-phenyl-thiazol-5-yl)-amide (Ia)

step 1: To a solution of Boc-L-Proline (4.5 g, 0.02 mmol) and pyridine(8.45 mL, 0.104 mmol) in DCM (20 mL) cooled in an ice bath was addeddropwise cyanuric fluoride (5.35 mL, 0.0627 mmol). After the additionthe reaction became milky. The solution was stirred at 0° C. for 10 minthen warmed to RT and stirred for 4 h. The reaction was quenched withwater, and thrice extracted with DCM. The combined organic extracts werewashed with brine, dried, and concentrated in vacuo to afford tert-butyl2-(fluorocarbonyl)pyrrolidine-1-carboxylate. The crude acid fluoride wasused in next coupling reaction immediately.

The freshly prepared acid fluoride (4.55 g, 0.02 mmol) was dissolved inMeCN (20 mL), and treated with 20 (1.7 g, 0.007 mmol) and pyridine (2.82mL, 0.035 mmol). The reaction was heated to 50° overnight. The reactionmixture was quenched with sat. NaHCO₃ and thrice extracted with EtOAc.The combined organic layers were washed with brine, dried andconcentrated. The crude product was purified by SiO₂ chromatographyeluting with an EtOAc/hexane gradient (50 to 80% EtOAc) to afford(S)-tert-butyl2-(2-(oxazol-2-yl)-4-phenylthiazol-5-ylcarbamoyl)pyrrolidine-1-carboxylate(21).

Removal of the Boc protecting group and sequential coupling withBocHN-Chg-OH and H(Me)N-Ala-OH were carried out in accord withprocedures in steps 2 and 3 of referential example 3. Purification ofthe Chg coupling product also was accomplished by SiO₂ chromatographyeluting with an EtOAc/hexane gradient (50 to 80% EtOAc). The crudeBoc-protected tripeptide product was purified by ISCO (50-80%EtOAc/Hexane). After remove of the Boc group the final product waspurified by Prep HPLC to afford pure Ia: (M+H)⁺=ms 565.3

Example 2

Other Compounds of this invention, e.g.,

-   1.    (S)-1-[(S)-2-cyclopropyl-2-((S)-2-methylamino-propionylamino)-acetyl]-pyrrolidine-2-carboxylic    acid (2-oxazol-2-yl-4-phenyl-thiazol-5-yl)-amide;-   2.    (S)-1-[(S)-2-cyclopentyl-2-((S)-2-methylamino-propionylamino)-acetyl]-pyrrolidine-2-carboxylic    acid (2-oxazol-2-yl-4-phenyl-thiazol-5-yl)-amide;-   3.    (S)-1-[(S)-2-cycloheptyl-2-((S)-2-methylamino-propionylamino)-acetyl]-pyrrolidine-2-carboxylic    acid (2-oxazol-2-yl-4-phenyl-thiazol-5-yl)-amide;-   4.    (S)-1-[(S)-2-cyclohexyl-2-((S)-2-ethylamino-propionylamino)-acetyl]-pyrrolidine-2-carboxylic    acid (2-oxazol-2-yl-4-phenyl-thiazol-5-yl)-amide;-   5.    (S)-1-[(S)-2-cyclohexyl-2-((S)-2-methylamino-propionylamino)-acetyl]-pyrrolidine-2-carboxylic    acid (2-oxazol-2-yl-4-phenyl-thiazol-5-yl)-N-methyl-amide; and-   6.    (S)-1-[(S)-2-cyclohexyl-2-((S)-2-methylamino-propionylamino)-2-methyl-acetyl]-pyrrolidine-2-carboxylic    acid (2-oxazol-2-yl-4-phenyl-thiazol-5-yl)-amide,

can be prepared analogously to the compound of Example 1 usingcorrespondingly analogous starting materials in the procedure of Example1.

Example 3 IAP Inhibition Assays

In the following experiments was used a chimeric BIR domain referred toas MLXBIR3SG in which 11 of 110 residues correspond to those found inXIAP-BIR3, while the remainder correspond to ML-IAP-BIR. The chimericprotein MLXBIR3SG was shown to bind and inhibit caspase-9 significantlybetter than either of the native BIR domains, but bound Smac-basedpeptides and mature Smac with affinities similar to those of nativeML-IAP-BIR. The improved caspase-9 inhibition of the chimeric BIR domainMLXBIR3SG has been correlated with increased inhibition ofdoxorubicin-induced apoptosis when transfected into MCF7 cells.

MLXBIR3SG Sequence:

MGSSHHHHHHSSGLVPRGSHMLETEEEEEEGAG

ATLSRGPAFPGMGSEELRLASFYDWPLTAEVPP

ELLAAAGFFHTGHQDKVRCFFCYGGLQSWKRGD

DPWTEHAKWFPGCQFLLRSKGQEYINNIHLTHSL

(SEQ ID NO.: 1)

TR-FRET Peptide Binding Assay

Time-Resolved Fluorescence Resonance Energy Transfer competitionexperiments were performed on the Wallac Victor2 Multilabeled CounterReader (Perkin Elmer Life and Analytical Sciences, Inc.) according tothe procedures of Kolb et al (Journal of Biomolecular Screening, 1996,1(4):203). A reagent cocktail containing 300 nM his-tagged MLXBIR3SG;200 nM biotinylated SMAC peptide (AVPI); 5 μg/mL anti-hisallophycocyanin (XL665) (CISBio International); and 200 ng/mLstreptavidin-europium (Perkin Elmer) was prepared in reagent buffer (50mM Tris [pH 7.2], 120 mM NaCl, 0.1% bovine globulins, 5 mM DTT and 0.05%octylglucoside). (Alternatively, this cocktail can be made usingeuropium-labeled anti-His (Perkin Elmer) andstreptavidin-allophycocyanin (Perkin Elmer) at concentrations of 6.5 nMand 25 nM, respectively). The reagent cocktail was incubated at roomtemperature for 30 minutes. After incubation, the cocktail was added to1:3 serial dilutions of an antagonist compound (starting concentrationof 50 μM) in 384-well black FIA plates (Greiner Bio-One, Inc.). After a90 minute incubation at room temperature, the fluorescence was read withfilters for the excitation of europium (340 nm) and for the emissionwavelengths of europium (615 nm) and a allophycocyanin (665 nm).Antagonist data were calculated as a ratio of the emission signal ofallophycocyanin at 665 nm to that of the emission of europium at 615 nm(these ratios were multiplied by a factor of 10,000 for ease of datamanipulation). The resulting values were plotted as a function ofantagonist concentration and fit to a 4-parameter equation usingKaleidograph software (Synergy Software, Reading, Pa.). Indications ofantagonist potency were determined from the IC50 values. Compounds ofthe invention where found to have IAP inhibitory activity which wasdemonstrated in this assay.

Fluorescence Polarization Peptide Binding Assay

Polarization experiments were performed on an Analyst HT 96-384(Molecular Devices Corp.) according to the procedure of Keating, S. M.,Marsters, J, Beresini, M., Ladner, C., Zioncheck, K., Clark, K.,Arellano, F., and Bodary., S.(2000) in Proceedings of SPIE: In VitroDiagnostic Instrumentation (Cohn, G. E., Ed.) pp 128-137, Bellingham,Wash. Samples for fluorescence polarization affinity measurements wereprepared by addition of 1:2 serial dilutions starting at a finalconcentration of 5 μM of MLXBIR3SG in polarization buffer (50 mM Tris[pH 7.2], 120 mM NaCl, 1% bovine globulins 5 mM DTT and 0.05%octylglucoside) to 5-carboxyflourescein-conjugated AVPdi-Phe-NH₂(AVP-diPhe-FAM) at 5 nM final concentration.

The reactions were read after an incubation time of 10 minutes at roomtemperature with standard cut-off filters for the fluoresceinfluorophore (λ_(ex)=485 nm; λ_(em)=530 nm) in 96-well black HE96 plates(Molecular Devices Corp.). Fluorescence values were plotted as afunction of the protein concentration, and the IC50s were obtained byfitting the data to a 4-parameter equation using Kaleidograph software(Synergy software, Reading, Pa.). Competition experiments were performedby addition of the MLXBIR3SG at 30 nM to wells containing 5 nM of theAVP-diPhe-FAM probe as well as 1:3 serial dilutions of antagonistcompounds starting at a concentration of 300 μM in the polarizationbuffer. Samples were read after a 10-minute incubation. Fluorescencepolarization values were plotted as a function of the antagonistconcentration, and the IC₅₀ values were obtained by fitting the data toa 4-parameter equation using Kaleidograph software (Synergy software,Reading, Pa). Inhibition constants (K_(i)) for the antagonists weredetermined from the IC₅₀ values. Compounds of the invention where foundto have IAP inhibitory activity which was demonstrated in this assay.For example, the value for K_(i) for compound Ia is 0.014 (ML-IAP-BIR).

Example 4 Tumor Xenograft Studies (FIGS. 1 and 2)

All procedures involving animals were performed in accordance with theguidelines of the Genentech Institutional Animal Care and Use Committee.Cancer cells such as Human breast MDA-MB-231, colorectal, Colo205, orNSCLC, Calu6 cancer cells were obtained from American Type CultureCollection (Manassas, Va.). Cells were resuspended in HBSS (Colo205) orthe cell suspension was mixed 1:1 with Matrigel (BD Biosciences;MDA-MB-231, Calu6). The cells (1.5×10⁷ for MDA-MB-231; 5.0×10⁷ forColo205, Calu6) were then implanted subcutaneously into the right flankof female nude mice (Charles River Laboratories, Hollister, Calif.) aged6-8 weeks. Tumor volumes were calculated using the mean diametermeasured with vernier calipers using the formula v=0.5×a×b², were a andb are the largest and smallest perpendicular tumor diameters,respectively. Ten mice with the appropriate mean tumor volume wereassigned randomly to each of six groups. The mean tumor volume±thestandard error of the mean (SEM) for all six groups was 168±3 mm³ at theinitiation of treatment (Day 0). The mice were observed on each day ofthe study, and tumor volumes and body weights were measured twice eachweek. Percent tumor growth inhibition was calculated using the formula %TGI=100×(1−Tumor Volume_(dose)/Tumor Volume_(vehicle)).

In this assay using human breast MDA-MB-231•X1 cells, Compound Ia of theinvention has an MED value of 3.4 mg/kg (iv Qwk). This is five timesless than the amount needed for prior art compound III in the same assayunder the same conditions (MED=18.6 mg/kg). The AUC for Ia is four timesless than that for III for similar efficacy.

The features disclosed in the foregoing description, or the followingclaims, expressed in their specific forms or in terms of a means forperforming the disclosed function, or a method or process for attainingthe disclosed result, as appropriate, may, separately, or in anycombination of such features, be utilized for realizing the invention indiverse forms thereof.

The foregoing invention has been described in some detail by way ofillustration and example, for purposes of clarity and understanding. Itwill be obvious to one of skill in the art that changes andmodifications may be practiced within the scope of the appended claims.Therefore, it is to be understood that the above description is intendedto be illustrative and not restrictive. The scope of the inventionshould, therefore, be determined not with reference to the abovedescription, but should instead be determined with reference to thefollowing appended claims, along with the full scope of equivalents towhich such claims are entitled.

The patents, published applications, and scientific literature referredto herein establish the knowledge of those skilled in the art and arehereby incorporated by reference in their entirety to the same extent asif each was specifically and individually indicated to be incorporatedby reference. Any conflict between any reference cited herein and thespecific teachings of this specifications shall be resolved in favor ofthe latter. Likewise, any conflict between an art-understood definitionof a word or phrase and a definition of the word or phrase asspecifically taught in this specification shall be resolved in favor ofthe latter.

We claim:
 1. A compound of formula I

wherein Ph is phenyl; R¹ is C₃₋₇ cycloalkyl; R², R³, R⁴, R⁵, and R⁶ areeach independently in each occurrence H or C₁₋₆ alkyl; or apharmaceutically acceptable salt thereof.
 2. The compound of claim 1which is(S)-1-[(S)-2-cyclohexyl-2-((S)-2-methylamino-propionylamino)-acetyl]-pyrrolidine-2-carboxylicacid (2-oxazol-2-yl-4-phenyl-thiazol-5-yl)-amide (Ia) or apharmaceutically acceptable salt thereof.
 3. A compound of claim 1wherein R²-R⁶ are each independently H or methyl.
 4. A compound of claim1 wherein R¹ is cyclohexyl.
 5. A compound of claim 3 wherein R¹ iscyclohexyl.
 6. A compound of claim 3 wherein one of R² and R³ is H andthe other is methyl; or R⁴ is methyl; or R⁵ and R⁶ are each H.
 7. Apharmaceutical composition comprising the compound of claim 1 and atleast one pharmaceutically acceptable carrier, diluent or excipient. 8.A pharmaceutical composition comprising the compound of claim 2 and atleast one pharmaceutically acceptable carrier, diluent or excipient.